NOTE:
An upgrade of Oracle Linux from a beta release is not supported.

Further, an in-place upgrade between major versions of Oracle Linux is not supported. Oracle does not recommend an upgrade from earlier major versions of Oracle Linux even though anaconda provides an option to do this upgrade. A fresh installation is strongly recommended rather than a system upgrade between major versions.

Customers who want to use new features in Unbreakable Enterprise Kernel can do so without upgrading to Oracle Linux 6 as Oracle Linux 5.8 already includes Unbreakable Enterprise Kernel.

Note: By default, both the Unbreakable Enterprise Kernel and the Red Hat Compatible Kernel for the specific architecture (i386 or x86_64) are installed, and the system boots the Unbreakable Enterprise Kernel by default. If needed, /etc/grub.conf and /etc/sysconfig/kernel can be modified to make the system boot with the Red Hat Compatible Kernel by default.

Unbreakable Enterprise Kernel Release 2

The Unbreakable Enterprise Kernel Release 2 is based on the upstream kernel 3.0.16 stable source tree.

This release of the Unbreakable Enterprise Kernel has been improved/enhanced by Oracle in several areas, including bug fixes and extended functionality. All of these modifications have been contributed back upstream and are available in mainline Linux.

Btrfs

Btrfs provides a flexible way to manage storage, without needing a separate volume manager. It provides built-in RAID support and ensures data integrity by using redundancy and checksums. Btrfs also supports lightweight copies/clones of files or directories with snapshots as well as online data compression. The Btrfs code in the Unbreakable Enterprise Kernel Release 2 includes many new features as well as numerous performance improvements, that were merged from a number of long running projects and cleanup queues.

Note: The standard installation media does not have support for creating a btrfs root filesystem on initial install. If you want to install Oracle Linux 6 Update 3 and use btrfs as your root filesystem, please use the alternative boot ISO media which uses btrfs as the default root filesystem. Using the boot.iso requires that the full installation source be available via a network method, i.e. FTP, HTTP or NFS.

New Btrfs features/functionality

An updated version of btrfsfsck, a tool to check and repair a Btrfs file system, is now included in the btrfs-progs package. This new btrfsck now supports a --repair option that allows fixing errors in the extent allocation tree and block group accounting. btrfsck also provides the option --init-csum-tree which replaces the check-sum root with an empty one. This will clear out the CRCs but allows the file-system to be mounted with the mount option nodatasum.

Scrubbing: you can initiate a check of the entire file system by triggering a file system scrub job that is performed in the background. The scrub run scans the entire file system for integrity and automatically attempts to report and repair any bad blocks it finds along the way. Instead of going through the entire disk drive, the scrub run only deals with data that is actually allocated. Depending on the allocated disk space, this is much faster than performing an entire surface scan of the disk.

LZO compression: In addition to the already existing zlib compression algorithm, data can now be alternatively compressed using LZO, which provides higher compression ratios and faster decompression for certain types of data.

Read-only snapshots

Different compression and copy-on-write settings for each file/directory (in addition to the per-filesystem controls). Btrfs compression can be controlled on a per file/directory basis. It can be enabled any time after a subvolume has been created. In the default mode, it will flag the file as not compressible and will not try to compress blocks again. In compress-force mode, Btrfs will keep trying for new writes, in case the newly added file content becomes compressable.

List all subvolumes on a file system (btrfs subvolume list)

List all files recently modified (btrfs subvolume find-new)

Allow changing the subvolume to be mounted by default with btrfs subvolume set-default (to better support snapshot-assisted distribution upgrades)

Now records a number of previous tree roots as backups, which can be useful in recovering damaged filesystems. If a given mount fails to go through because a tree root is bad, you can now use mount -o recovery and Btrfs will walk through the array and try to mount older versions of the file system.

Btrfs bug fixes and performance improvements

Asynchronous creation of snapshots. Avoids waiting for the snapshot to be committed to disk.

Significantly improved ls readdir() performance

Switched the btrfs tree locks to reader/writer

Improvements to the logging code. Lots of data was logged more than once, greatly increasing the I/O load. Log I/O traffic has been cut to ~25% of the previous level.

Allow to overcommit ENOSPC reservations (speeds up a test from 45 minutes to 10 seconds)

Fixed regressions in the mount and general error handling code, which also fixes some problems in the mount -o autodefrag mode

Tweaked the ENOSPC throttling. The file system tries to start I/O to make sure it can do all the allocations that it has promised to do. The end result is a dramatic improvement in random write workloads among many others.

Improved the scrubber and provided utilities to walk Btrfs' many backrefs. The scrubber is much faster thanks to extensive btree readahead and instead of just informing the user that a specific block is bad, it tells him which btree or which file was impacted by that bad block.

Fixed the Btrfs cache flushing. This one probably explains many of the corruptions that have been reported, especially on multi-device filesystems. Ceph users running with -o notreelog were dramatically more likely to trigger the corruptions. The problem was that Btrfs was triggering cache flushes before the last copy of the super block, instead of doing them before the first copy. Take extra care about getting flushes done to all the devices in a multi-device FS before writing any of the supers.

Xen domU improvements

Several bug fixes and improvements have been incorporated to make the Unbreakable Enterprise Kernel scale and cooperate better as a guest (domU) in Oracle VM and Xen.

Xen block backend from Linux 3.3 kernel. This provides the fully featured Xen blkback along with extra features, such as passing through a flush (a lighter version of barrier), discard (also known as TRIM or SCSI UNMAP) and various bug-fixes and enhancments.

Xen PCI backend from Linux 3.3 kernel, this includes the option to specify how the PCI structure shows up in the PV guest - either as in host or virtualized; Fixes to make it work with SR-IOV VF cards; and numerous mutex fixes.

Memory self-ballooning - allows the guest to automatically balloon depending on the workload.

Other improvements

dm-nfs: device-mapper target that allows you to treat an NFS file as a block device. It provides loopback-style emulation of a block device using a regular file as backing storage. The backing file resides on a remote system and is accessed via the NFS protocol.

Upgrading to Oracle Linux 6 Update 3

As Oracle Linux 6 Update 3 now ships with the latest Unbreakable Enterprise Kernel Release 2, upgrading via the installation media will evaluate whether or not to install this latest kernel based on the currently installed kernel.

If you have an existing Oracle Linux 6 GA, Update 1 or Update 2 install that does not have the already released Unbreakable Enterprise Kernel Release 2 installed, the Oracle Linux 6 Update 3 media will not install this kernel by default. Note that the Oracle Linux 6 Update 3 installation media does not contain any updates to the original Unbreakable Enterprise Kernel, so in this scenario, only the latest Red Hat Compatible Kernel will be installed.

If you have an existing Oracle Linux 6 GA, Update 1 or Update 2 install that already has the released Unbreakable Enterprise Kernel Release 2 installed, the Oracle Linux 6 Update 3 media will install the latest version of this kernel.

Upgrades that are performed via YUM will use whatever repositories are configured to upgrade the system. The latest Unbreakable Enterprise Kernel Release 2 can be found in the ol6_<arch>_UEK_latest repository, i.e. either ol6_i386_UEK_latest or ol6_x86_64_UEK_latest. You should ensure that this repository is enabled either via the Unbreakable Linux Network or in the /etc/yum.repos.d/public-yum-ol6.repo file if you want to install this kernel.

Known Issues

This can occur on Oracle VM 3.0 if the guest is set with a maximum memory (maxmem) parameter greater than the amount set at boot (memory). To avoid this issue, please ensure the maxmem and memory parameters are equal. This issue has been resolved in Oracle VM 3.1.1.

Post-install Anaconda Errors

In certain cases, after successfully completing installation and rebooting the system, it is possible that the following error stack appears:

These errors would also be logged in anaconda.log in /root after installation. These errors can safely
be ignored.

Cannot start FCoE Target service with Unbreakable Enterprise Kernel

The upstream release has added support for FCoE target service. This is not supported with the previous release of the Unbreakable Enterprise
Kernel (2.6.32). Customers wishing to use this service must boot into the Unbreakable Enterprise Kernel Release 2 (2.6.39) or the Red Hat Compatible Kernel.

This service is not supported with the previous release of the Unbreakable Enterprise Kernel (2.6.32). Customers wishing to use this service must boot into the Unbreakable Enterprise Kernel Release 2 (2.6.39) or the Red Hat Compatible Kernel.

mlx4_core conflicts between mlnx_en and ofa packages

Both the new mlnx_en and ofa packages contain mlx4_core. Only one of the two packages should be installed. Attempts to install both packages on a single server will result in a package conflict error. To determine which package to use, if you have a Mellanox Ethernet Controller, please use mlnx_en. If you have a Mellanox Infiniband Controller, please use ofa. If you have both, please use ofa as it supports both Ethernet and Infiniband controllers.

kdump service fails to start with Unbreakable Enterprise Kernel

When configuring the crash kernel for the UEK, only standard crash kernel settings, e.g. crashkernel=128M@32M, are supported. The new setting used
by the RHCK, i.e. crashkernel=auto, is not supported and will cause the kdump service to fail to start.

The Unbreakable Enterprise Kernel adds support for paravirtualized drivers in a HVM guest on Oracle VM. The default is to present only paravirtualized drivers when running in a hardware virtualized guest. To run kernel-uek --including the drivers-- fully hardware virtualized, an additional kernel boot parameter "xen_emul_unplug=never" must be added to the boot parameters in /etc/grub.conf:

Oracle Linux 6 defaults to strict reverse path filtering. Some Oracle products and network storage devices work more reliably when using loose reverse path filtering. To enable loose mode reverse path filtering, issue the following command (assuming you are changing settings for the network interface called eth1). The default setting is 1.

If, during installation on an x86_64 system, the pam.i386 package is installed either manually or via package dependency, and the oracle-rdbms-server-11gR2-preinstall package is also selected, the Oracle Database related settings in /etc/security/limits.conf will be overwritten by the installation of the pam.i386 package. This is most likely to occur when using a kickstart-based automated installation that includes non-standard package selections. To restore these settings, run the oracle-rdbms-server-11gR2-preinstall-verify script.

Unbreakable Linux Network

After an install of Oracle Linux 6, the screens after the first reboot will guide you to register your system to the Unbreakable Linux Network (ULN). If you did not configure your network during the initial installation, the registration process to ULN will not succeed. In this case, you should configure your network by running NetworkManager first (as root). Then restart the ULN registration by running uln_register (as root).

Console appears to hang while booting on certain systems (10094052)

On some hardware, the console may appear to hang during the boot process after starting udev. But the system does boot up properly and is accessible. A workaround to this problem is to add nomodeset as a kernel boot parameter in /etc/grub.conf:

For the Unbreakable Enterprise Kernel, the default IO scheduler is the 'deadline' scheduler.
For the Red Hat Compatible Kernel, the default IO scheduler is the 'cfq' scheduler.

sched_yield() settings for CFS

For the Unbreakable Enterprise Kernel, kernel.sched_compat_yield=1 by default.
For the Red Hat Compatible Kernel, kernel.sched_compat_yield=0 by default.

Technology Preview Features

The following Technology Preview features are currently not supported under Oracle Linux 6 and may not be functionally complete:

Open multicast ping (Omping)

Matahari

System Information Gatherer and Reporter (SIGAR)

fsfreeze

DIF/DIX support

File system in user space (FUSE)

LVM Application Programming Interface (API)

LVM RAID support

FS-Cache

vios-proxy

IPv6 support in IPVS

Trusted boot

TPM

The following Technology Preview features are only available when running the Red Hat Compatible Kernel (RHCK):

Parallel NFS

Brocade BFA driver

SR-IOV on the be2net driver

Support for Fiber Channel over Ethernet (FCoE) target mode

Kernel Media support

Remote audit logging

Linux (NameSpace) Container [LXC]

Error Detection And Correction (EDAC) driver interface

Diagnostic pulse for the fence_ipmilan agent

System monitoring via SNMP

Wire speed requirement in KVM network drivers

KVM Live Snapshots

These features are not suitable for production use. However, these features are included to provide the feature with wider exposure.

Configuring Updates for Oracle Linux 6 Update 3

Oracle Linux 6 no longer contains up2date for access to Unbreakable Linux Network. Instead packages are managed using Yum. To register with ULN, use the following command:

# uln_register

Unbreakable Linux Network

To access Linux updates via Unbreakable Linux Network, you must purchase a Linux support subscription. For more information please visit http://linux.oracle.com.

During ULN registration the server will be automatically registered with two channels: the latest channel for the base repository as well as the latest channel for the Unbreakable Enterprise Kernel Release 2. If you have upgraded from a previous release and do not wish the UEK Release 2 to be installed, you will need to manually unsubscribe the server from this channel.

The Unbreakable Linux Network includes Oracle-specific software packages, for example Oracle's ASMlib userspace package and the Oracle Instant Client. To enable access to these packages, login to the Unbreakable Linux Network and subscribe to the "Oracle Software" channel.

Public Yum

Oracle now provides all errata and updates for Oracle Linux via the public yum service. This service does not require a Linux support subscription, but only includes updates to the base distribution and does not include Oracle-specific software. To enable updates via public-yum, please visit http://public-yum.oracle.com and follow the instructions on that website.

By default, all new installs of Oracle Linux 6 Update 3 are automatically configured to use the public-yum update service. No modification is required to use this service. The public-yum service is automatically disabled when a server is registered with the Unbreakable Linux Network.

Installation Media

Note: Oracle Linux 6 Update 3 now contains two distinct repository sources on the installation media. To configure yum to use the installation media as a yum source, create the following file /etc/yum.repos.d/Media.repo with content similar to the following: